Centrifugal speed control device



Patented Mar. 31, 1953 UNITED STATES- EATENT. OFFICE CENTRIFUGAH SPEED CONTROL DEVICE William-A. Engstrom; MuskegomMich,.assignor;

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Applicationflpulyilfl, 1946;Srial .Noz1682i5dll;

2JClaims; 1..

This invention relates to a speed control device such as a speed governor used on internal combustion engines.

A problem in the speed governing of internal combustion engines is how to make the governing device capable of functioning at various selected speeds.

It is an object of this invention to provide a speed governor which can be set to function at any of a number of selected speeds within a wide range, without necessitating the use of difierent governor springs.

This and other objects will be accomplished by the use of a movable spring anchor, the anchor being guided in a definite path by means of a slot in an anchor plate.

Fig. 1 is an elevational view of the governor and control mechanism, and

Fig. 2 is a graph illustrating the action of the present governor with respect to engine operation.

Fig. l of the drawing shows a governor housing 2 in which is disposed any suitable speed responsive device. An arm 4 is connected to be oscillated by the governor and is connected to actuate throttle valve 6 through the connection 8. A spring I0 is connected under tension to the arm 4 to bias the throttle valve 6 toward its open position. As can be seen in the drawing, spring I0 is provided with a movable anchor I2. Anchor [2 is movable through a definite path by means of S-shaped slot 14 in the anchor plate I6. Plate I6 is mounted on the governor housing. The operator of the engine controls the position of anchor l2 in the slot by means of rod 18.

As will be understood by those skilled in the art, the efiective moment arm of spring is the perpendicular distance from pivot to a line drawn between point 22 and anchor l2. It is evident from a study of the drawing that the ends of slot [4 between the points A and B and between the points C and D are so positioned in relation to points 20 and 22 as to produce great changes in spring tension for unit movement of anchor I 2, and relatively small Changes (almost zero) in the moment arm. Furthermore, movement of anchor 12 in the slot between points B and C will produce great changes in the moment arm, but small changes in the spring tension.

It is of course understood that points A and D represent the ends of slot l4, or the extreme limits of travel of the anchor l 2. The location of points B and C in the S-shaped slot is not critical. Points B and. C will be understood to be located where the curvature of the slot is such as to change from horizontal and vertical to mostly 2 horizontal, as shown in the drawing. For purposes of convenience, it may be said that i the given embodiment, points B and C represent those points of the slot at which a tangent to the curve forms an angle with the horizontal of approximately thirty degrees. This angle is of course not critical.

The essential feature of the invention is that the anchor I2 move through a path which is so defined that unit movement at the ends of the path produces great changes in spring tension and small changes in moment arm, whereas movement in the intermediate part of the path produces small changes in spring tension and great changes in the moment arm.

The main purpose of the above described structure is to obtain a desired regulation at various engine speeds, or in other words, to obtain the same speed variable from no load to full load over a broad variation of speeds. Thus at X power at 1000 R. P. M. the governor is constructed to cut out power at 1000 R. P. M. and to eiTect this regulation over a speed range of about R. P. M. If the governor is set to operate at 1500 R. P. M.

v or 2000 R. P. M. it will result in the same regulation as at 1000 R. P. M. Without this curved slot A, B, C, D, the desired regulation is difierent for different speeds, as for instance, the power curve will fall 01f on curve 30a for 1000 R. P. M. or as 50c for 2000 R. P. M. The present governor is operable to give a power curve 30 at 1000 R. P. M., 40 at 1500 R. P. M. and 50 at 2000 R. P. M., or in other words, we have the same regulation over a broad variation of speeds. The diagram Fig. 2 is illustrative of this principle of operation.

I claim:

1. In a governor, a regulable spring device connected tobias a pivoted arm of a speed responsive device, said spring being connected at one end to said arm, a fixed supporting plate for said spring and having an S-shaped slot, said other end of said spring being adjustably anchored in said S-shaped slot, one end portion of said slot adjacent to the pivotal center of said arm being curved toward the point of attachment of said spring with the arm and the other end portion of said S-shaped slot being curved away from the point of attachment of said spring with the arm, the shifting of the adjustable spring anchor means in one direction effecting a rapid accelerated reduction in spring tension together with a pronounced accelerated decrease in the efiective moment arm of said spring, and the shifting of the adjustable spring anchor means in the other direction efiecting a rapid accelerated increase in spring tension and an increase in the efiective moment arm of said spring.

2. In a governor, a regulable spring device connected to bias a pivoted arm of a speed responsive device, said spring being connected at one end to said arm, a supporting plate for said spring and having an S-shaped slot, said other end of said spring being movably anchored in said S-shaped slot, and means to adjustably locate the spring anchor in said slot, said slot being so constructed as to dispose the curved end portion adjacent to the pivotal center of said arm toward the point of attachment of said spring with the arm, the shifting of the adjustable spring anchor means in one direction toward said arm effecting a rapid accelerated reduction in spring tension together with a pronounced accelerated decrease in the effective moment arm of said spring, and the shifting of the adjustable spring anchor means in the other direction away from said arm effecting 4 a rapid accelerated increase in spring tension and an increase in the efiective moment arm of said spring.

WILLIAM A. ENGSTROM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,055,834 Tibbetts Mar. 11, 1913 1,074,495 Davis Sept. 30, 1913 1,086,173 Hill Feb. 3, 1914 1,655,681 Standerwick et a1. Jan. 10, 1928 1,954,864 Crafts Apr. 17, 1934 2,287,036 Hufiord June 23, 1942 2,356,202 Benjamin Aug. 22, 1944 2,424,503 Reger July 22, 1947 2,437,883 Mallory Mar. 16, 1948 

